quiz 2 key - 1. Which of the following peptides has an...

1. Which of the following peptides has an overall net positive charge? To answer this question, you need to know the 1 letter code and which amino acids are charged. Basic amino acids have net positive charge (K, R and H) and acidic amino acids have a net negative charge (D and E). a. MAVEDPKLCM charge=-1(E)-1(D)+1(K)= -1 b. MIRLNKSTVQY charge=+1(R)+1(K)= +2 c. MHFDLVNEKA charge=+1(H)-1(D)-1(E)+1(K)= 0 d. MPAGNWIQLS charge=-0 2. The DNA double helix is more rigid than the alpha-helix because it has many more hydrogen bonds holding it together. T False : Since the H-bonds are perpendicular to the axis of the helix, bending doesn’t break these bonds. On the other hand, the alpha helix is held together by h-bonds that are parallel to the axis of the helix. When the alpha helix bends, it breaks these bonds. Hence the alpha helix is more rigid than the double helix. 3. β-pleated sheets a. are held together by hydrogen bonds between the strands true b. are the only secondary structure found in antibodies.

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